Just charge NOTHING and request the amenity retroactively via Gold Passport. Instead of 1,000 points, you would receive 1,500 points because the hotel "forgot" to post the amenity.

If the hotel insists to charge $1, I would fight this as a matter of principle.

They didn't insist, they informed us about the need for a charge if the amenity were to be posted and offered to put on a $1 charge if we didn't charge anything to the room. Thinking back, I think that we did not end up spending anything extra and I didn't think about it when departed, so we just did a separate credit request and it worked out fine.